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Geitner, Nicholas. « A Study of Gold Nanoparticles for Application in Semiconductor CdS Nanosheet Biosensor Devices ». Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1311893825.
Texte intégral
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Pujalte, Igor. « Étude in vitro de la toxicité de nanoparticules métalliques (TiO2, ZnO, CdS) sur la cible rénale ». Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21849/document.
Texte intégralRésumé :
De nombreuses incertitudes persistent sur la toxicité potentielle des nanoparticules (NPs) et leur devenir dans l’organisme humain. L’objectif de ce travail est de mieux comprendre les mécanismes cytotoxiques induits par des NPs métalliques sur une cible secondaire, représentée par le rein. En effet, les NPs sont susceptibles de franchir les barrières cellulaires, d’être véhiculées par le sang pour se retrouver filtrées par le rein au niveau des cellules glomérulaires et peut-être, réabsorbées au niveau des cellules tubulaires. Cette étude est réalisée in vitro, avec des NPs métalliques de titane (TiO2 : 12 nm), de zinc (ZnO : 75 nm) et de cadmium (CdS : 8 nm), sur cellules mésangiales (IP15) et cellules épithéliales tubulaires (HK-2). Les résultats démontrent des effets variables selon le type cellulaire étudié, la nature chimique des NPs et leur solubilité. Si les NPs insolubles de TiO2 (CI50>100 µg/cm²) ne sont que très peu toxiques, les NPs de CdS et de ZnO le sont bien plus du fait de leur solubilité (CI50<7 µg/cm²). La libération de cations métalliques Cd2+ et Zn2+ est à l’origine de cette toxicité. La production d’ERO et la perturbation du statut oxydatif cellulaire (GSH/GSSG) sont corrélées aux effets cytotoxiques des NPs de ZnO et CdS. Une approche moléculaire permet d’identifier les voies de signalisation cellulaire intervenant dans la réponse au stress (translocation nucléaire des facteurs de transcription : Nrf2 et NF-κB). L’internalisation et l’accumulation, des NPs de TiO2 et de CdS, sont responsables de l’induction d’un stress oxydant et d’un effet cytotoxique lors d’exposition sur le long termeMany uncertainties remain about the potential toxic effect of nanoparticles (NPs), and their becoming in human organism. The aim of this study was to understand the cytotoxic mechanisms induced by metallic NPs, on a secondary target organ, the kidney. NPs were able to cross biological barriers, be carried in blood to kidney cells, on glomerular or tubular cells. This study was performed in vitro, with NPs of titanium (TiO2: 12 nm), zinc (ZnO: 75 nm) and cadmium (CdS: 8 nm), on mesangial IP-15 cells and epithelial HK-2 cells. Results showed effects depending on cell type, chemical nature of NPs and their solubility. TiO2 NPs have no cytotoxic effect (IC50>100µg/cm²), probably due to their insolubility. Exposure to CdS and ZnO NPs lead to cell death (IC50< 7 µg/ cm²). Release of metallic cations Cd2+ and Zn2+ are the main causes of toxicity. ROS production and disruption of oxidative cellular balance (GSH/ GSSG) were correlated to the cytotoxic effects of ZnO and CdS NPs. A molecular approach was used to identify signaling pathways involved in oxidative stress response (nuclear translocation of NF-kappaB and Nrf2).Internalization and accumulation of TiO2 and CdS NPs were responsible of oxidative stress induction and cytotoxic effect on long term exposure
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Lama, Bimala. « Synthesis and Characterization of CdS Nanoparticle/Polymer Composites ». University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1375797236.
Texte intégral
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Rho, Young Gyu. « Quantum-Confined CdS Nanoparticles on DNA Templates ». Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc279352/.
Texte intégralRésumé :
As electronic devices became smaller, interest in quantum-confined semiconductor nanostructures increased. Self-assembled mesoscale semiconductor structures of II-VI nanocrystals are an especially exciting subject because of their controllable band gap and unique photophysical properties. Several preparative methods to synthesize and control the sizes of the individual nanocrystallites and the electronic and optical properties have been intensively studied. Fabrication of patterned nanostructures composed of quantum-confined nanoparticles is the next step toward practical applications. We have developed an innovative method to fabricate diverse nanostructures which relies on the size and a shape of a chosen deoxyribonucleic acid (DNA) template.
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Mirfin, Tayla Michele. « Targeted delivery of GFP loaded polymeric nanoparticles to CD4 expressing cells using a CD4 specific aptamer ». University of the Western Cape, 2020. http://hdl.handle.net/11394/8184.
Texte intégralRésumé :
>Magister Scientiae - MScHuman Immunodeficiency Virus (HIV), which is the cause of Acquired Immunodefiency Syndrome (AIDS) is a major global public health issue affecting over 37 million people worldwide and is responsible for claiming over 32 million lives since the discovery of the disease in 1981. Through effective diagnosis, treatment and prevention HIV is a manageable disease. Today, advanced antiretrovirals, known as HAART, serve as effective, first-line drug regimens, consisting of a variety of viral inhibitors, and have successfully helped viral suppression. However, issues arise with antiretrovirals due to patient non-adherence and the development of drug resistant mutations. Coupled with dormant HIV reservoirs, viral extinction is attenuated. It is therefore essential that effective alternative treatments are investigated. The exploration of nanomedicine for targeted drug delivery has shown an ability to prolong the drug circulation time, target drugs to specific sites in the body, and enhance drug effectiveness. A previous study demonstrated a novel therapeutic strategy that was based on a mutant version of the caspase-3 enzyme that can induce apoptosis in HIV infected cells. This therapeutic strategy has the potential to wipe out reservoirs of HIV infection. However, the therapeutic strategy lacked selectivity because the delivery mechanism was based on protein transduction technology which will result in the nonselective delivery of the drug. In this study, preliminary work towards the development of a targeted nanoparticle delivery system for this mutant caspase-3 enzyme is described. The study describes the synthesis of green fluorescent protein loaded alginate/chitosan nanoparticles that were functionalized with a DNA aptamer intended to target the nanoparticles to CD4 expressing cells, that are also targeted by HIV. The THP-1 cell line was used due to the ability of the cells to express CD4 receptors on the cell surface. The nanoparticles were synthesized through ionotropic gelation. The size, polydispersity, zeta potential and morphology were investigated by Dynamic Light Scattering and Scanning Electron Microscopy, respectively. The strongly negative zeta potential studies revealed stability of the nanoparticles in suspension and Scanning Electron Microscopy results showed an indicative collapse of the polymer network for the empty nanoparticles (i.e. nanoparticles not loaded with GFP), whereas solid, cuboid nanoparticles were shown for the GFP-loaded nanoparticles. Image-based fluorescence cytometry demonstrated that the GFP-loaded nanoparticles bind to the THP-1 cells that express the CD4 receptor. The results obtained are indicative of a potential drug delivery system for HIV treatment however, adjustments would need to be made to the current study to further develop this nanocarrier.
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Li, Adrienne Victoria. « Immunization with synthetic nanoparticles to generate mucosal CD8 T Cell responses ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/80255.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, February 2013Cataloged from PDF version of thesis. "September 2012."
Includes bibliographical references (p. 97-110).
Vaccines have benefited global health by controlling or eradicating life threatening diseases. With better understanding of infectious diseases and immunity, more interest has been placed on stimulating mucosal immune responses with vaccines as mucosal surfaces function as a first line of defense against infections. Progress made in nanoparticle research, in particular the successful use of liposomes for drug delivery, has made liposomes an attractive candidate for vaccine delivery. Here, we investigate the efficacy of using a novel nanoparticle system, Interbilayer Crosslinked Multilamellar Vesicles (ICMVs), as a mucosal vaccine to stimulate mucosal and systemic CD8 immunity. We first assessed the ability of ICMVs to elicit mucosal CD8 response, against the model antigen ovalbumin (OVA), by administration of the nanoparticles through the lungs. We explored the use of 2 different Toll-like receptor agonists (TLRa), monophosphoryl lipid A (MPLA) and Polyinosinic:polycytidylic acid (poly (I:C) or pIC) added to ICMVs as adjuvants. Pulmonary administration of ICMV with both adjuvants was found to give the most potent CD8 T cell response in both systemic and mucosal compartments. We looked further into the quality of the immune response and detected the presence of antigenspecific memory CD8 T cells in the system at ~2.5 months after immunization. The majority of these cells were found to be effector memory cells (CD44hiCD62Llo) and expressed markers for long term survival (CD127hiKLRG1lo), suggesting that long term protection against infection can be induced by pulmonary delivery of ICMVs. We also explored using this system to deliver a model HIV peptide epitope, AL 1, and ICMV successfully induced CD8 response against this epitope. Animals immunized against AL 11 were challenged with a live virus expressing the same epitope and protection was seen only in the pulmonary ICMV treatment group. Virus was delivered via the lungs and viral titre was decreased in both the lungs and ovaries. Neither the soluble form of the vaccine or ICMV delivered via parenteral injection conferred protection. Safety of the ICMV system was also assessed and no significant negative effects were observed in body weight and histological analysis on lungs. Finally, mechanism of using nanoparticles as pulmonary vaccines was investigated to gain better understanding in how particulate vaccine and route of immunization improved the efficacy of a vaccine. Overall, this thesis describes a comprehensive study of systemic and mucosal CD8 responses generated by pulmonary delivery of a novel nanoparticle system. This data provides evidence that mucosal delivery of ICMVs can safely and effectively stimulate disseminated mucosal CD8+ T cells at sites relevant for protection against mucosal infection. A better understanding of nanoparticles for pulmonary immunization was also gained.
by Adrienne Victoria Li.
Ph.D.
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Suryajaya. « Study of electrostatically self-assembled thin films of CdS and ZnS nanoparticle semiconductors ». Thesis, Sheffield Hallam University, 2007. http://shura.shu.ac.uk/20410/.
Texte intégralRésumé :
In this work, CdS and ZnS semiconducting colloid nanoparticles coated with organic shell, containing either SO[3-] or NH[2+] groups, were deposited as thin films using the technique of electrostatic self-assembly. The films produced were characterized with UV-vis spectroscopy and spectroscopic ellipsometry - for optical properties; atomic force microscopy (AFM) - for morphology study; mercury probe - for electrical characterisation; and photon counter - for electroluminescence study. UV-vis spectra show a substantial blue shift of the main absorption band of both CdS and ZnS, either in the form of solutions or films, with respect to the bulk materials. The calculation of nanoparticles' radii yields the value of about 1.8 nm for both CdS and ZnS.The fitting of standard ellipsometry data gave the thicknesses (d) of nanoparticle layers of around 5 nm for both CdS and ZnS which corresponds well to the size of particles evaluated from UV-vis spectral data if an additional thickness of the organic shell is taken into account. The values of refractive index (n) and extinction coefficient (k) obtained were about 2.28 and 0.7 at 633 nm wavelength, for both CdS and ZnS.Using total internal reflection (TIRE), the process of alternative deposition of poly-allylamine hydrochloride (PAH) and CdS (or ZnS) layers could be monitored in-situ. The dynamic scan shows that the adsorption kinetic of the first layer of PAH or nanoparticles was slower than that of the next layer. The fitting of TIRE spectra gavethicknesses of about 7 nm and 12 nm for CdS and ZnS, respectively. It supports the suggestion of the formation of three-dimensional aggregates of semiconductor nanoparticles intercalated with polyelectrolyte. AFM images show the formation of large aggregates of nanoparticles, about 40-50 nm, for the films deposited from original colloid solutions, while smaller aggregates, about 12-20 nm, were obtained if the colloid solutions were diluted. Current-voltage (I-V) and capacitance-frequency (C-f) measurements of polyelectrolyte/nanoparticles (CdS or ZnS) films suggest the tunnelling behaviour in the films while capacitance- voltage (C-V) and conductance-voltage (G-V) measurements suggest that these nanoparticles are conductive. The electroluminescence was detected in sandwich structures of (PAH/CdS/PAH)[N] using a photon counting detector, but not in the case of ZnS films.
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Mohamad, Syed Abdul Malik Syed. « Electrical studies on hybrid MIS structures incorporating CdS nanoparticles in organic films ». Thesis, Sheffield Hallam University, 2005. http://shura.shu.ac.uk/20004/.
Texte intégralRésumé :
This project involves the investigation of a.c. and d.c. electrical characterisations and low-frequency noise properties of Langmuir-Blodgett (LB) films in metal-insulator-semiconductor (MIS) structure. Two types of insulating films based on hybrid organic-inorganic materials sandwiched between metal and semiconductor were fabricated. The original insulating films (untreated) were 40 layers Y-type LB films of Cd-salt stearic acid (CdSt[2]). The second type of insulating films were formed after the treatment of CdSt[2] films with H[2]S gas over a period of 12 hours at room temperature to grow CdS nanoparticles within the stearic acid matrix (treated). The capacitance-voltage (C-V) measurement of CdSt[2] LB films exhibit significant dependence on the measurement frequency in the accumulation region due to high d.c. leakage currents. By embedding CdS nanoparticles into the stearic acid matrix, less frequency dependent C-V curves were obtained. The problem in determining the true insulator capacitance due to frequency dispersion was overcome by using the Yang's model. The corresponding dielectric constant of LB films of CdSt[2] was found to be 2.3 and increased to 5.1 when embedded with CdS nanoparticles. The results from the dielectric loss measurement show that both devices agree well with Goswami and Goswami model. By incorporating CdS nanoparticles in the stearic acid matrix, the dielectric loss was found to increase which could be due to electrons being trapped by the CdS nanoparticles. A large current density was observed in the untreated devices at room temperature giving evidence of a leaky dielectric. The analysis of the temperature dependent I-V characteristics shown that current is independent of temperature, similar to the results published by several researchers which explained the current conduction mechanism in term of electron hopping and tunnelling through each bilayer of the LB films. In contrast, by embedding the CdS nanoparticles in the stearic acid matrix the currents have reduced by one-order of magnitude. The temperature dependence of the I-V characteristics showed the dependence of current on the device temperature at low electric field densities whilst less temperature dependence was observed at higher electric field density. Further investigation into the carrier transport mechanism, has found that the Poole-Frenkel effect was the dominant mechanism in the treated devices. A low frequency noise measurement setup has been designed and validated. The results of low-frequency noise measurement reported here are new. 1 / f noise was the only low-frequency noise observed in treated and untreated devices for frequencies up to 1kHz. The current noise spectral density S[I](f), was found to fit well with themodified Hooge's empirical model; [mathematical formula] where C, /, and f are noisemagnitude, current and frequency respectively. The exponential values of gamma and beta were found to lie within the acceptable ranges of 0.7 < gamma < 1.4 and 1 < beta < 3 respectively. The current noise power spectral density (PSD) at several fixed bias current was found to be dependent on the bias current with the PSDs for treated devices found to be approximately two-orders of magnitude higher. These results show that low-frequency noise measurement can be used to probe into the microstructure of the electron devices. It is believed that by embedding the CdS nanoparticles into the stearic acid matrix, electron trapping centres have been created which result in different current conduction behaviour from the untreated LB films of cadmium stearate.
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Mousavi, R. A., A. A. Sepahy et M. R. Fazeli. « Biosynthesis, Purification and Characterization of Cadmium Sulfide Nanoparticles Using Enterobacteriaceae and their Application ». Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34903.
Texte intégralRésumé :
The area of nanotechnology encompasses the synthesis of nanoscale materials, the understanding and
the utilization of their physicochemical and optoelectronic properties, and the organization of nanoscale
structures into predefined superstructures. The development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. Nanotechnology has recently emerged as an elementary division of science and technology that investigates and regulates the interaction at cell level between synthetic and biological materials with the help of nanoparticles.
A wide range clean, nontoxic and eco-friendly synthesis of nanoparticles is an important aspect of current
nanotechnology. Microbial synthesis of nanoparticles is a Green chemistry approach that interconnects
nanotechnology and microbial biotechnology. Microorganisms play an important role in the eco-friendly
synthesis of metal nanoparticles. This study illustrates the synthesis of CdS nanoparticles using the bactetia of Enterobacteriaceae ( Escherichia coli PTCC 1533 and Klebsiella pneumonia PTCC 1053) after 96 h of
incubation at room temperature (30ºc) and pH 9. The morphology of the samples was analyzed using Scanning electron microscopy(SEM). The size of CdS nanoparticles in aqueous solution has been calculated using UV–Vis spectroscopy, XRD, FTIR, EDS and SEM measurements. The nanoparticles are found to be
polydisperse in the size range 5–200 nm.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34903
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Hill, Lawrence J. « Synthesis and Dipolar Assembly of Cobalt-Tipped CdSe@CdS Nanorods ». Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/332684.
Texte intégralRésumé :
This dissertation contains four chapters with advances relevant to the fields of nanoparticle synthesis and nanoparticle self-assembly: a review of nanoparticle self-assembly, or “colloidal polymers”; dumbbell heterostructured nanorod synthesis; dipolar matchstick heterostructured nanorod synthesis; and self-assembly of dipolar matchsticks to form colloidal polymers. These chapters are followed by appendices containing supporting data for chapters two through four. The first chapter is a review summarizing current research involving the 1-D assembly of nanocrystals to form “colloidal polymers.” One of the major goals of materials chemistry is to synthesize hierarchical materials with precise controlled particle ordering covering all length scales of interest (termed, the “bottom up” approach). Recent advances in the synthesis of inorganic colloids have enabled the construction of complex morphologies for particles in the range of 1 – 100 nm. The next level of structural order is to control the structure of assemblies formed from these materials. Linear nanoparticle assemblies are particularly challenging to achieve due to the need to impart functionality to colloids such that (typically) only two sites are active per particle. An emerging idea in the literature which addresses this challenge is to consider linear assemblies of inorganic nanoparticles as colloidal analogs to traditional polymers. This conceptual framework has enabled the formation of linear assemblies having controlled composition (to form segmented and statistical copolymers), architecture (linear, branched, cyclic), and degree of polymerization (chain length). However, this emerging field of synthesizing colloidal polymers has not yet been reviewed in terms of methods to control fundamental polymer parameters. Therefore, linear nanoparticle assembly is reviewed in chapter 1 by applying concepts from traditional polymer science to nanoparticle assembly. The emphasis of chapter 1 is on controlling degree of polymerization, architecture, and composition for colloidal polymers, and seminal examples are highlighted which control these parameters. The second chapter is centered on a novel methodology to install ferromagnetic cobalt domains onto core@shell, “CdSe@CdS” nanorods. While the structures synthesized in this work were novel, the key advance from this work was the development of a methodology to separate nanorod activation from deposition of ferromagnetic cobalt domains onto semiconductor nanorods. As synthesized CdSe@CdS nanorods are passivated with strongly binding phosphonic acid ligands, and these ligands prevent direct deposition of many materials (such as cobalt). Synthetic methods must therefore modify nanorod surfaces prior to deposition of additional nanoparticle domains (tips). Previous synthetic methods for the deposition of magnetic domains onto nanorod termini typically combined activation of nanorod termini and metal deposition into a single synthetic step. While these previous reports were successful in achieving tipped nanorods, the coupling of these two reactions required matching the kinetics of nanorod activation and decomposition/reduction of metal precursors in order to achieve the desired heterostructure morphology. However, the presence of ligands used for nanorod activation can also affect the rate of metal precursor decomposition/reduction and the propensity of the metal to form free nanoparticles through homogeneous nucleation. Thus, simultaneous nanorod activation and metal deposition hinders modification of these syntheses to obtain differing heterostructured morphologies. In the work presented in chapter 2, we chemically activate nanorod termini towards cobalt deposition in a separate chemical step from deposition of metallic cobalt nanoparticle domains. First, reductive platinum deposition conditions were utilized to activate nanorod termini towards the deposition of cobalt domains, which were deposited in a subsequent reaction step. Then, the kinetics of nanorod activation during platinum deposition were tracked, and the platinum-tipped nanorod morphologies were correlated with the results of subsequent cobalt deposition reactions. Ultimately, controlled placement of cobalt domains onto one or both nanorod termini was demonstrated based on the degree of activation during platinum deposition. Cobalt nanoparticle tips were then selectively oxidized to form CoₓOy-tipped nanorods, which were a novel class of p-n type nanomaterials achieved over a total of five synthetic steps. Relevant supporting details for the synthesis of these dumbbell tipped nanorods are provided in Appendix A. The third chapter describes the synthesis of CoNP-tipped nanorods with a single, strongly dipolar, ferromagnetic CoNP-tip per nanorod. The key synthetic advance was the ability to activate a single terminus per nanorod without activation of lateral nanorod facets, which was vital in achieving these larger, dipolar, cobalt tips (rather than lateral decoration of cobalt onto nanorod lateral facets). These dipolar “matchstick” CoNP-tipped nanorods then spontaneously formed linear assemblies carrying nanorod side chains as pendant functionality. Activation of CdSe@CdS nanorods was found to occur through the deposition of small (< 2 nm) PtNP-tips which were not readily observable by standard characterization techniques. The finding that small (< 2 nm) PtNP-tips altered nanorod reactivity towards cobalt deposition emphasized the effect of subtle changes to nanorod surface chemistry. Relevant supporting details for the synthesis of these dipolar matchstick tipped nanorods are provided in appendix B. The fourth chapter is centered on the self-assembly of dipolar matchstick cobalt-tipped nanorods to form colloidal (co)polymers reminiscent of traditional bottlebrush polymers, with controlled composition and phase behavior on carbon surfaces. Similar to earlier findings in traditional polymer science, nanorod side chain length was found to significantly impact surface assembly of these colloidal analogs of bottlebrush copolymers, which provided a useful parameter for affecting surface wetting and phase behavior of nanoparticle thin films. This work was also the first demonstration of colloidal copolymers from the dipolar assembly of magnetic nanoparticles, where both segmented and statistical copolymer compositions were achieved. We then demonstrated, for the first time, that a colloidal copolymer with segmented composition can form a mesoscopic phase separated morphology which is similar to that observed for traditional block copolymers. This key advance opens the possibility of controlling structural ordering over still longer length scales by the development of methods to control phase separated morphologies in a manner similar to traditional block copolymers. Relevant supporting details for the synthesis and assembly of these colloidal bottlebrush polymers are provided in appendix C.
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Sachdeva, Parveen. « LATTICE VIBRATION STUDY OF SILICA NANOPARTICLE IN SUSPENSION ». Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3345.
Texte intégralRésumé :
In recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of nanoparticles. In this work atomic scale simulation has been used to study possible mechanisms affecting the heat transfer characteristics of nanofluids. Molecular dynamics simulation for a single silica nanoparticle surrounded by water molecules has been performed. Periodic boundary condition has been used in all three directions. The effect of nanoparticle size and temperature of system on the thermal conductivity of nanofluids has been studied. It was found that as the size of nanoparticle decreases thermal conductivity of nanofluid increases. This is partially due to the fact that as the diameter of nanoparticle decreases from micrometer to nanometer its surface area to volume ratio increases by a factor of 103. Since heat transfer between the fluid and the nanoparticle takes place at the surface this enhanced surface area gives higher thermal conductivity for smaller particles. Thermal conductivity enhancement is also due to the accumulation of water molecules near the particle surface and the lattice vibration of the nanoparticle. The phonon transfer through the second layer allows the nanofluid thermal conductivity to increase by 23%-27% compared to the base fluid water for 2% concentration of nanosilica.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
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Hoff, Richard. « Iron Oxide Nanoparticle Surface Modification : Synthesis and Characterization ». Master's thesis, Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/592997.
Texte intégralRésumé :
BioengineeringM.S.
Multifunctional nanomaterials can be engineered to aid in the diagnosis of diseases, enable efficient drug delivery, monitor treatment progress over time, and evaluate treatment outcomes. This strategy, known as theranostics, focuses on the combination of diagnostic and therapeutic techniques to provide new clinically safe and efficient personalized treatments. The evaluation of different nanomaterials’ properties and their customization for specific medical applications has therefore been a significant area of interest within the scientific community. Iron oxide nanoparticles, specifically those based on iron (II, III) oxide (magnetite, Fe3O4), have been prominently investigated for biomedical, theranostic applications due to their documented superparamagnetism, high biocompatibility, and other unique physicochemical properties. The aim of this thesis is to establish a viable set of methods for preparing magnetite (iron oxide) nanoparticles through hydrothermal synthesis and modifying their surfaces with organic functional groups in order to both modulate surface chemistry and facilitate the attachment of molecules such as peptides via covalent bond formations. Modifying their surfaces with biomolecules such as peptides can further increase their uptake into cells, which is a necessary step in the mechanisms of their desired biomedical applications. The methods of nanoparticle synthesis, surface functionalization, and characterization involving electron microscopy (e.g., SEM, TEM), zeta potential measurements, size analysis (i.e., DLS), and FT-IR spectroscopy will be presented.
Temple University--Theses
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Garcia, Saida Y. « A Characterization of CdS/Polymer Interactions by Solid State Nuclear Magnetic Resonance ». University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1240277763.
Texte intégral
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Alterary, Seham. « Synthèse, caractérisation et fonctionnalisation de CdS et de suspensions magnétiques collïdales en vue d'application biomolécules ». Paris 7, 2008. http://www.theses.fr/2008PA077230.
Texte intégralRésumé :
Lors de cette thèse, deux axes ont été développés. La première partie du manuscrit a été consacrée au développement de nanocristaux pour des applications biologiques, Dans un premier temps, nous avons réussi la synthèse de nanoparticules de CdS_fonctionnalisées par des oligothiophènes carboxylates. Ces ligands carboxyliques forment une couche compacte autour des nanocristaux ce qui permet leur dispersion dans l'eau. Ces nano-structures fonctionnalisées ont été caractérisées par différentes techniques. La taille des particules peut être contrôlée entre 2 et 4 nm. La fonctionnalisation par la biotine a été réalisée grâce un ester activé, le N-hydroxysuccinimide. Des essais de détection de l’ayidine ont démontré la capacité de ces particules à détecter une substance biologique. La deuxième partie du manuscrit est focalisée sur le développement de nouvelles structures nanométrique core-shell. Dans cette partie nous avons mis au point une méthode de synthèse sol-gel pour l'encapsulation homogène des nanoparticules magnétiques d'une couche de silice dont l'épaisseur est contrôlable. Les nanoparticules cœur magnétique et écorce silice sont ensuite caractérisées par différentes méthodes physico-chimiques. Nous avons réussi à démontrer, clairement la possibilité d'élaborer des nanoparticules structurées présentant un cœur magnétique et une écorce de siliceSemiconductor quantum dots (QDs) are a new generation of inorganic probes with advantageous properties over traditional organic probes for biological applications. A major hurdle in the use of QDs for biology is the inability of the hydrophobically synthesized QDs to interface with aqueous environments. In the first part of this dissertation we describe the synthesis of water-soluble CdS QDs end-capped with N-hydroxysuccinimide ester groups, with narrow size distribution. These CdS QDs are synthesized in polyol medium using terthiophene dicarboxylic acid as a stabilizer. The structure of the hybrid product was investigated by TEM, XRD, optical and FTIR spectroscopy. The modifîed nanoparticles consist of a few tens of oligothiophène units attached to the CdS core. The free carboxylic end groups were transformed into 7V-hydroxysuccinimidyl ester and were further cross-linked with biotin and avidin. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicate successful modification of CdS QD surfaces. The second part, describes the synthesis and the characterization of hybrid magnetic core-shell structures. The Stöber method bas been adopted to prepare hybrid core-shell particles by coating the surfaces of monodisperse magnetic emulsion with uniform silica shells. The Stöber method has been adopted to prepare hybrid core-shell particles by coating the surfaces of monodisperse magnetic emulsion with uniform silica shells. The coated particles have been characterized by electron microscopy (TEM), XPS spectroscopy and IR and showing a core shell structure with a uniform layer of silica
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Mukundarajan, Sriram. « Synthesis of Alkylthiol-containing Fluorene Derivatives for Gold Nanoparticle Functionalization ». Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3570.
Texte intégralRésumé :
A novel synthetic methodology has been developed for attaching fluorene derivatives, containing different types of electron donating and accepting groups at the 2 and 7 positions, to gold nanoparticles of different sizes by exploiting the affinity of the thiol functional group for gold. The distance between the dye and nanoparticles was varied by introducing two alkyl chains containing different number of carbon atoms at the 9 position on the fluorene ring system. The methodology that was developed gave enough scope for performing Radiative Decay Engineering (RDE) studies, in order to investigate the impact of gold nanoparticles on the singlet oxygen quantum yields of fluorene dyes that already exhibit high singlet oxygen quantum yields as well as high two photon absorption (2PA) cross-sections. The dialkylation of the fluorene derivatives was accomplished by reacting the dye with [alpha], [omega]-dibromoalkanes containing different number of carbon atoms in a biphasic reaction mixture containing toluene and aqueous sodium hydroxide solution in the presence of tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. The bromine atom on the alkyl chains was converted to thioester by reaction with potassium thioacetate. This was followed by the hydrolysis of the thioester to form the thiol moiety. The compounds synthesized were characterized using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Functionalization of gold nanoparticles was attempted by bringing into contact a solution of the thiol compound in toluene and an aqueous gold nanoparticles solution. UV-vis absorbance spectroscopy was used to monitor the progress of the attachment. Surface Enhanced Raman Scattering (SERS) spectroscopy was used to probe the enhancement of Raman signal by the metallic nanoparticles.M.S.
Department of Chemistry
Arts and Sciences
Industrial Chemistry
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Hao, Junjie. « Revisiter la chiralité induite et la photodéposition d'or sur des semi-conducteurs CdSe/CdS possédant différentes morphologies contrôlées ». Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0186.
Texte intégralRésumé :
Des morphologies contrôlées de nanocristaux de semi-conducteurs II – VI traditionnels à base de cadmium (NCs) sont présentées. Différentes morphologies peuvent être obtenues en utilisant le processus d'extraction et de purification à la tri-n-octylphosphine (TOP), tels que les nanodots, les nanofleurs, les têtards, les bâtonnets (dot-in-rods) et les tétrapodes. Les objets appelés CdSe/CdS (DRs) ont été spécifiquement choisis pour la poursuite de l'étude sur la chiralité et la photodéposition en raison de leur chiralité potentielle induite par le ligand et de leurs performances catalytiques. Le mécanisme de transmission chirale induite par un ligand a été étudié par un procédé top-down de gravure de domaine sélectif. Les résultats ont montré que lors de la comparaison des signaux de chiralité d'une nanoparticule individuelle, la couche de coquille avait un impact négatif sur la chiralité du premier pic d'exciton, mais une corrélation positive sur la chiralité d'absorption de la coquille. Nous présentons pour la première fois les signaux de luminescence à polarisation circulaire (CPL) de chiralité induite dans des nanoplaquettes deCdSe / CdS (NPL) synthétisées par une approche en une étape. La chiralité des nanocristaux semi-conducteurs de morphologies différentes induite par le ligand est étudiée plus en détail, et les activités de dichroïsme circulaire (CD) et de CPL observées sont étroitement associées aux caractères géométriques des nanostructures tels que l'épaisseur de la coque et le rapport d'aspect des NR CdSe/CdS . Enfin, le mécanisme de croissance par photodéposition induite par laser de nanocristaux d'or sur des bâtonnets préformés de CdSe/CdS (DRs) est abordé. Les nanoparticules HNPs Au-CdSe/CdS sont obtenues en utilisant une lumière laser bleue. Les effets du capteur de trous pour la synthèse des HNPs à pointe unique sont étudiés en profondeur pour la première fois. De plus, d'autres paramètres sont également étudiés, tels que l'intensité d'irradiation, le temps de dépôt, le rapport Au / DRs, etc. Nos résultats sont en bon accord avec un modèle développé pour la croissance d'un seul nanocristal Au en surface du DRControlled morphologies of traditional cadmium-based II–VI semiconductor nanocrystals (NCs) are presented. Different morphologies can be achieved by using the tri-n-octylphosphine (TOP) extraction and purification process, such as nanodots, nanoflowers, tadpoles, dot-in-rods and tetrapods. CdSe/CdS dot-in-rods (DRs) were specifically chosen for the further study on chirality and photodeposition due to its potential ligand-induced chirality and catalytic performances. The mechanism of ligand-induced chiral transmission was studied by the top-down selective domain etching process. The results showed that when comparing the chirality signals of an individual nanoparticle, the shell layer had a negative correlation with the first exciton peak chirality, but positive correlation with the shell absorption chirality. We present the induced chirality circularly polarized luminescence (CPL) signals in CdSe/CdS nanoplates (NPLs) synthesized by a one-pot approach for the first time. The ligand induced chirality of semiconductor nanocrystals with different morphologies are further studied, and the observed circular dichroism (CD) and CPL activities are closely associated to the geometrical characters of the nanostructures such as the shell thickness and the aspect ratio of the CdSe/CdS Tadpoles. Finally, the laser-induced photodeposition growth mechanism of gold nanocrystals onto preformed CdSe@CdS dot-in-rods (DRs) is presented. The hybrid NPs (HNPs) Au-CdSe/CdS are achieved by using a blue-laser light. The effects of the hole scavenger for the synthesis of single-tipped HNPs are studied deeply for the first time. Additionally, other parameters are also studied, such as the irradiation intensity, the deposition time, the Au/DRs ratio and so on. Our results compare quite well with a model developed for the growth of single Au nanocrystal
17
Cheng, Huaitzung Andrew. « Development of Polyphenolic Nanoparticles for Biomedical Applications ». Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/384200.
Texte intégralRésumé :
BioengineeringPh.D.
Polymeric nanoparticles have a wide range of applications, particularly as drug delivery and diagnostic agents, and tannins have been regarded as a promising building block for redox and pH responsive systems. Tannins are a class of naturally occurring polyphenols commonly produced by plants and are found in many of our consumables like teas, spices, fresh fruits, and vegetables. Many of the health benefits associated with these foods are a result of their high tannin contents and the many different types of tannins found in various plants have demonstrated therapeutic potentials for conditions ranging from cardiovascular disease and diabetes to ulcers and cancer. Diets rich in tannins have been associated with lower blood pressure in patients with hypertension. The plurality of phenols in tannins also makes them powerful antioxidants and as a result, there is a lot of interest in taking advantage of their self-assembling abilities to make redox and pH responsive drug delivery systems. However, the benefit of natural tannins is limited by their instability in physiological conditions. Furthermore, there is limited control over molecular weight and reactivity of the phenolic content of plant extracts. Herein we report the novel synthesis of pseudotannins with control over molecular weight and reactivity of phenolic moieties. These pseudotannins have can form nanoscale interpolymer complexes under physiological conditions and have demonstrated antioxidative potential. Furthermore, pseudotannin IPCs have been shown to be responsive to physiologically relevant oxidation as well as the ability to easily incorporate cell targeting peptides, fluorescent tags, and MRI contrast agents. The work presented here describes how pseudotannins would be ideally suited to minimally invasive techniques for diagnosing atherosclerotic plaques and targeting triple negative breast cancer. We demonstrate that pseudotannin can very easily and quickly form nanoscale particles that are small enough to be uptaken into mammalian cells. Furthermore, by self-assembling with gadolinium, pseudotannins can effectively attenuate the signal of gadolinium based MRI contrast agents. This in conjunction with oxidation responsive decomplexation could be a viable option for diagnosing the severity and risk of rupture of atherosclerotic plaques. Also, we demonstrate that pegylated compounds can easily be incorporated into pseudotannin nanoparticles to impart cell targeting functionality. The subsequent uptake of pseudotannin nanoparticles into breast cancer cells demonstrated the ability to increase their sensitivity to UV radiation. The creation of synthetic tannin-like polymers leads to directly to making a variety of self-assembling, stimuli responsive, and bioactive nanoparticles well-suited for various biomedical applications.
Temple University--Theses
18
Dai, Qiu. « SURFACE ENGINEERING OF GOLD NANOPARTICLES AND THEIR APPLICATIONS ». Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3557.
Texte intégralRésumé :
Gold nanoparticles (AuNPs) with their unique sizes, shapes, and properties have generated much enthusiasm over the last two decades, and have been explored for many potential applications. The successful application of AuNPs depends critically on the ability to modify and functionalize their surface to provide stability, compatibility, and special chemical functionality. This dissertation is aimed at exploring the chemical synthesis and surface modification of AuNPs with the effort to (1) control the number of functional groups on the particle surface, and to (2) increase the colloidal stability at the physiological conditions. To control the functionality on the particle surface, a solid phase place exchange reaction strategy was developed to synthesize the 2 nm AuNPs with a single carboxylic acid group attached on the particle surface. Such monofunctional AuNPs can be treated and used as molecular nanobuilding blocks to form more complex nanomaterials with controllable structures. A "necklace"-like AuNP/polymer assembly was obtained by conjugating covalently the monofunctional AuNPs with polylysine template, and exhibited an enhanced optical limiting property due to strong electromagnetic interaction between the nanoparticles in close proximity. To improve the colloidal stability in the psychological condition, biocompatible polymers, polyacrylic acid (PAA), and polyethylene glycol (PEG) were used to surface modify the 30 nm citrate-stabilized AuNPs. These polymer-modified AuNPs are able to disperse individually in the high ionic strength solution, and offer as the promising optical probes for bioassay applications. The Prostate specific antigen (PSA) and target DNA can be detected in the low pM range by taking advantages of the large scattering cross section of AuNPs and the high sensitivity of dynamic light scattering (DLS) measurement. In addition to the large scattering cross section, AuNPs can absorb strongly the photon energy at the surface plasmon resonance wavelength and then transform efficiently to the heat energy. The efficient photon-thermal energy conversion property of AuNPs has been used to thermal ablate the Aβ peptide aggregates under laser irradiation toward Alzheimer's disease therapy.Ph.D.
Department of Chemistry
Sciences
Chemistry PhD
19
Wang, Chaoming. « THERMAL DETECTION OF BIOMARKERS USING PHASE CHANGE NANOPARTICLES ». Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3877.
Texte intégralRésumé :
Most of existing techniques cannot be used to detect molecular biomarkers (i.e., protein and DNA) contained in complex body fluids due to issues such as enzyme inhibition or signal interference. This thesis describes a nanoparticle-based thermal detection method for the highly sensitive detections of multiple DNA biomarkers or proteins contained in different type of fluids such as buffer solution, cell lysate and milk by using solid-liquid phase change nanoparticles as thermal barcodes. Besides, this method has also been applied for thrombin detection by using RNA aptamer-functionalized phase change nanoparticles as thermal probes. Furthermore, using nanostructured Si surface that have higher specific area can enhance the detection sensitivity by four times compared to use flat aluminum surfaces. The detection is based on the principle that the temperature of solid will not rise above its melting temperature unless all solid is molten, thus nanoparticles will have sharp melting peak during a linear thermal scan process. A one-to-one correspondence can be created between one type of nanoparticles and one type of biomarker, and multiple biomarkers can be detected simultaneously using different type nanoparticles. The melting temperature and the heat flow reflect the type and the concentration of biomarker, respectively. The melting temperatures of nanoparticles are designed to be over 100°C to avoid interference from species contained in fluids. The use of thermal nanoparticles allows detection of multiple low concentration DNAs or proteins in a complex fluid such as cell lysate regardless of the color, salt concentration, and conductivity of the sample.M.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr MSMSE
20
Korsvik, Cassandra. « Free Radical Scavenging Properties of Cerium Oxice Nanoparticles ». Honors in the Major Thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1178.
Texte intégralRésumé :
This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Burnett College of Biomedical Sciences
Molecular Biology and Microbiology
21
Hroch, Daniel. « Vertikálně uspořádaná pole CdS nanotyčinek pro aplikace v solárních článcích ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254222.
Texte intégralRésumé :
This thesis describes the deposition of nanoparticles into nanoporous alumina templates. Nanoparticles of cadmium sulphide were chosen thanks to wide band gap of 2,45 eV. CdS is desired semiconductor promising better efficiency when comes to solar radiation conversion to useful energy. Theoretical part consists of explanation of photovoltaic principles, band-gap theory of materials, currently available technologies to manufacture solar cells and their efficiencies. Next part introduces the approaches of manufacturing nanoporous templates from aluminium (Anodized Aluminium Oxide, AAO) in details together with options to deposit cadmium sulphide into these structures. There is also brief description of deposition based on vacuum filtration. Experiments were made in Laboratory of Microsensors and Nanotechnologies at Faculty of Electrical Engineering and Communication in Brno University of. The experimental chapter describes manufacturing process of AAO and deposition via vacuum filtration. Samples were evaluated by Scanning Electron Microscopy.
22
Ono, Luis. « IN-SITU GAS PHASE CATALYTIC PROPERTIES OF METAL NANOPARTICLES ». Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3277.
Texte intégralRésumé :
Recent advances in surface science technology have opened new opportunities for atomic scale studies in the field of nanoparticle (NP) catalysis. The 2007 Nobel Prize of Chemistry awarded to Prof. G. Ertl, a pioneer in introducing surface science techniques to the field of heterogeneous catalysis, shows the importance of the field and revealed some of the fundamental processes of how chemical reactions take place at extended surfaces. However, after several decades of intense research, fundamental understanding on the factors that dominate the activity, selectivity, and stability (life-time) of nanoscale catalysts are still not well understood. This dissertation aims to explore the basic processes taking place in NP catalyzed chemical reactions by systematically changing their size, shape, oxide support, and composition, one factor at a time. Low temperature oxidation of CO over gold NPs supported on different metal oxides and carbides (SiO2, TiO2, TiC, etc.) has been used as a model reaction. The fabrication of nanocatalysts with a narrow size and shape distribution is essential for the microscopic understanding of reaction kinetics on complex catalyst systems ("real-world" systems). Our NP synthesis tools are based on self-assembly techniques such as diblock-copolymer encapsulation and nanosphere lithography. The morphological, electronic and chemical properties of these nanocatalysts have been investigated by atomic force microscopy (AFM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD). Chapter 1 describes briefly the basic principles of the instrumentation used within this experimental dissertation. Since most of the state-of-art surface science characterization tools provide ensemble-averaged information, catalyst samples with well defined morphology and structure must be available to be able to extract meaningful information on how size and shape affect the physical and chemical properties of these structures. In chapter 2, the inverse-micelle encapsulation and nanosphere lithography methods used in this dissertation for synthesizing uniformly arranged and narrow size- and shape-selected spherical and triangular NPs are described. Chapter 3 describes morphological changes on individual Au NPs supported on SiO2 as function of the annealing temperature and gaseous environment. In addition, NP mobility is monitored. Chapter 4 explores size-effects on the electronic and catalytic properties of size-selected Au NPs supported on a transition metal carbide, TiC. The effect of interparticle interactions on the reactivity and stability (catalyst lifetime) of Au NPs deposited on TiC is discussed in chapter 5. Size and support effects on the formation and thermal stability of Au2O3, PtO and PtO2 on Au and Pt NPs supported on SiO2, TiO2 and ZrO2 is investigated in chapter 6. Emphasis is given to gaining insight into the role of the NP/support interface and that played by oxygen vacancies on the stability of the above metal oxides. Chapter 7 reports on the formation, thermal stability, and vibrational properties of mono- and bimetallic AuxFe1-x (x = 1, 0.8, 0.5, 0.2, 0) NPs supported on TiO2(110). At the end of the thesis, a brief summary describes the main highlights of this 5-year research program.Ph.D.
Department of Physics
Sciences
Physics PhD
23
Noll, Alexander J. « Cerium oxide nanoparticles for the detection of antimicrobial resistance ». Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/486.
Texte intégralRésumé :
The rise of antimicrobial resistance demands the development of more rapid screening methods for the detection of antimicrobial resistance in clinical samples to both give the patient the proper treatment and expedite the treatment of patients. Cerium oxide nanoparticles may serve a useful role in diagnostics due to their ability to exist in a mixed valence state and act as either oxidizing agents or reducing agents. Considering that cerium oxide nanoparticles have been shown to shift in absorbance upon oxidation, a useful method of antimicrobial resistance detection could be based on the oxidation of cerium oxide nanoparticles. Herein, an assay is described whereby cerium oxide nanoparticle oxidation is a function of glucose metabolism of bacterial samples in the presence of an antimicrobial agent. Cerium oxide nanoparticles were shown to have an absorbance in the range of 395nm upon oxidation by hydrogen peroxide whereas mixed valence cerium oxide nanoparticles lacked an absorbance around 395nm. In the presence the hydrogen peroxide-producing glucose oxidase and either increasing concentrations of glucose or bacterial medium supplemented with increasing concentrations of glucose, cerium oxide nanoparticles were shown to increase in absorbance at 395nm. This oxidation assay was capable of measuring differences in the absorbance of E. coli and S. aureus samples grown in the presence of inhibitory and non-inhibitory concentrations of ampicillin in as little as six hours. Therefore, this cerium oxide nanoparticle oxidation assay may be very useful for use in clinical laboratories for the detection of antimicrobial resistance due to the relatively low cost, no requirement for specialized equipment and, most importantly, the reduced incubation time of the assay to as little as six hours compared to current gold standard antimicrobial resistance detection methods that require 24 hours.; This assay may thus also help partially circumvent the issue of knowledge of antimicrobial resistance in infected patients before prescribing improper regimens.B.S.
Bachelors
Medicine
Molecular Biology and Microbiology
24
Menezes, Roseline. « Synthesis, characterization and antibacterial activity of silver embedded silica nanoparticle/nanogel formulation ». Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4804.
Texte intégralRésumé :
The antibacterial property of silver (Ag) has been known since ancient time. It is reported in the literature that silver nanoparticles (AgNPs) exhibit improved antibacterial properties in comparison to silver ions of equivalent metallic Ag concentration. Such improvement in antibacterial activities is due to the high surface area to volume ratio of AgNPs (which facilitates interaction with the bacterial cells), increased release of silver ions and direct intra-cellular uptake of AgNPs leading to localized release of Ag ions. To date, over 300 consumer products containing AgNPs are available in the market and the inventory is rapidly expanding. The antibacterial efficacy is related to the loading of AgNPs (which controls availability of active Ag ions). It is perhaps challenging to increase AgNPs loading in consumer products without compromising its aesthetic appearance. AgNPs exhibit yellow-brown color due to strong Surface Plasmon Resonance (SPR) absorption; and therefore, it is expected that an increase in loading would change the color of AgNP-containing materials. For applications, such as creating a fast-acting touch-safe surface, higher loading of AgNPs is desirable. It is also desirable to obtain a non-color forming surface. To meet the demands of desirable higher loading of AgNPs and non-color forming surface, the objective of this study is to minimize SPR by engineering Ag containing nanomaterials for potential fast-acting spray-based applications. Within this thesis several reports have been made including synthesis, characterization and antibacterial properties of Ag-loaded silica nanoparticle/nanogel (AgSiNP/NG) material containing nanoformulations. The effects of nanoformulation pH and metallic Ag content on the SPR absorption and antibacterial properties have been studied. The AgSiNP/NG materials were synthesized using silica sol-gel technique at room temperature in water.; The color formation of the AgSiNP/NG material was found to be dependent on silver ion loading (15.4 wt% and 42.3 wt %) as well as on the pH (pH 4.0 and pH 7.0). A number of material characterization techniques such as HRTEM, SEM and AFM were used to characterize particle size, crystalline and surface morphology in dry state. Dynamic light scattering (DLS) technique was used to characterize particle size and size distribution in solution. UV-VIS spectroscopy technique was applied to characterize Ag ions and AgNPs in the AgSiNP/NG material. Antibacterial studies were conducted against gram negative E.coli and gram positive B.subtilis and S.aureus. A number of qualitative (well diffusion, BacLight[Trademark] live-dead viability) and quantitative (turbidity, resazurin viability) assays were used for antibacterial studies. It was observed that lower pH and low Ag loading minimized SPR absorption, resulting in no yellow-brown color formation. The HRTEM confirmed the formation of ~5-25 nm size highly crystalline AgNPs which were coated with dielectric silica layer (silica gel). AFM, SEM and DLS studies confirmed formation of AgSiNPs in the range between 100 nm-200 nm. The AgSiNP/NG material was effective against both gram-negative and gram-positive bacteria. Based on this research it is suggested that by coating AgNPs with a dielectric material (such as silica); it is possible to suppress SPR absorption.ID: 031001357; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Title from PDF title page (viewed May 3, 2013).; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 74-79).
M.S.
Masters
Molecular Biology and Micro
Medicine
Biotechnology
25
Clukay, Christopher J. « Gold nanoparticle generation using in situ reduction on a photoresist polymer substrate ». Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/361.
Texte intégralRésumé :
This report presents evidence that in-situ reduction of metal ions bound to a cross-linked polymer surface does not always result in nanoparticle formation solely at the interface, as is commonly assumed, but also as much as 40 nm deep within the polymer matrix. Tetrachloroaurate ions were bound using a variety of multi-functional amines to cured films of SU-8 -- a cross-linkable epoxide frequently used for micro- and nanofabrication -- and then treated using one of several reducing agents. The resulting gold-nanoparticle decorated films were examined by X-ray photoelectron spectroscopy and by plan-view and cross-sectional transmission electron microscopy. Reduction using sodium borohydride or sodium citrate generates bands of interspersed particles as much as 40 nm deep within the polymer, suggesting both the Au(III) complex and the reducing agent are capable of penetrating the surface and affecting reduction and formation of nanoparticles within the polymer matrix. It is shown that nanoparticle formation can be confined nearer to the polymer interface by using hydroquinone, a sterically bulkier and less flexible reducing agent, or by reacting the surface in aqueous media with high molecular-weight multifunctional amines, that presumably confine Au(III) nearer to the true interface. These finding have important implications for technologies that apply surface bound nanoparticles, including electroless metallization, catalysis, nano-structure synthesis, and surface enhanced spectroscopy.B.S.
Bachelors
Sciences
Chemistry
26
Yildirim, Handan. « STRUCTURAL, ELECTRONIC, VIBRATIONAL AND THERMODYNAMICAL PROPERTIES OF SURFACES AND NANOPARTICLES ». Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3533.
Texte intégralRésumé :
The main focus of the thesis is to have better understanding of the atomic and electronic structures, vibrational dynamics and thermodynamics of metallic surfaces and bi-metallic nanoparticles (NPs) via a multi-scale simulational approach. The research presented here involves the study of the physical and chemical properties of metallic surfaces and NPs that are useful to determine their functionality in building novel materials. The study follows the  bottom-up approach for which the knowledge gathered at the scale of atoms and NPs serves as a base to build, at the macroscopic scale, materials with desired physical and chemical properties. We use a variety of theoretical and computational tools with different degrees of accuracy to study problems in different time and length scales. Interactions between the atoms are derived using both Density Functional Theory (DFT) and Embedded Atom Method (EAM), depending on the scale of the problem at hand. For some cases, both methods are used for the purpose of comparison. For revealing the local contributions to the vibrational dynamics and thermodynamics for the systems possessing site-specific environments, a local approach in real-space is used, namely Real Space Green s Function method (RSGF). For simulating diffusion of atoms/clusters and growth on metal surfaces, Molecular Statics (MS) and Molecular Dynamics (MD) methods are employed.Ph.D.
Department of Physics
Sciences
Physics PhD
27
Covone, Simon Armando Mostafa. « Synthesis, structure, and catalytic properties of size-selected platinum nanoparticles ». Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4656.
Texte intégralRésumé :
The use of heterogeneous catalysis is well established in chemical synthesis, energy, and environmental engineering applications. Supported Pt nanoparticles have been widely reported to act as catalysts in a vast number of chemical reactions. In this report, the performance of Pt/ZrO2 nanocatalyst for the decomposition of methanol, ethanol, 2-propanol, and 2-butanol is investigated. The potential of each alcohol for the production of H2 and other relevant products in the presence of a catalyst is studied. All the alcohols studied show some decomposition activity below 200[degrees]C which increased with increasing temperature. In all cases, high selectivity towards H2 formation is observed. With the exception of methanol, all alcohol conversion reactions lead to catalyst deactivation at high temperatures (T greater than]250[degreesC for 2-propanol and 2-butanol, T greater than]325[degrees]C for ethanol) due to carbon poisoning. However, long-term catalyst deactivation can be avoided by optimizing reaction conditions such as operating temperature. In addition, the performance of Pt/gamma]-Al2O3 is evaluated in the oxidation of 2-propanol. Pt nanoclusters of similar size (~1 nm diameter) but different structure (shape) were found to display distinctively different catalytic properties. All the systems studied achieve high conversion (~ 90%) below 100[degrees]C. However, flatter particles display a lower reaction onset temperature, demonstrating superior catalytic performance. Acetone, CO2, and water are generated as products indicating that both partial and complete oxidation are taking place. A number of techniques including AFM, XPS, TEM, HAADF-TEM, XAFS as well as packed-bed reactor experiments were used for sample characterization and evaluation of catalytic performance.ID: 028916890; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2010.; Includes bibliographical references (p. 84-92).
M.S.
Masters
Department of Civil, Environmental, and Construction Engineering
Engineering and Computer Science
28
Haque, Md Firoze H. « Single-electron transport spectroscopy studies of magnetic molecules and nanoparticles ». Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4914.
Texte intégralRésumé :
Magnetic nanoparticles and molecules, in particular ferromagnetic noble metal nanoparticles, molecular magnet and single-molecule magnets (SMM), are perfect examples to investigate the role of quantum mechanics at the nanoscale. For example, SMMs are known to reverse their magnetization by quantum tunneling in the absence of thermal excitation and show a number of fundamental quantum mechanical manifestations, such as quantum interference effects. On the other hand, noble metal nanoparticles are found to behave ferromagnetically for diameters below a few nanometers. Some of these manifestations are still intriguing, and novel research approaches are necessary to advance towards a more complete understanding of these exciting nanoscale systems. In particular, the ability to study an isolated individual nanoscale system (i.e just one molecule or nanoparticle) is both challenging technologically and fundamentally essential. It is expected that accessing to the energy landscape of an isolated molecule/nanoparticle will allow unprecedented knowledge of the basic properties that are usually masked by collective phenomena when the systems are found in large ensembles or in their crystal form. Several approaches to this problem are currently under development by a number of research groups. For instance, some groups are developing deposition techniques to create patterned thin films of isolated magnetic nanoparticles and molecular magnets by means of optical lithography, low-energy laser ablation, or pulsed-laser evaporation or specific chemical functionalization of metallic surfaces with special molecular ligands. However, it is still a challenge to access the properties of an individual molecule or nanoparticle within a film or substrate. I have studied molecular nanomagnets and ferromagnetic noble metal nanoparticles by means of a novel experimental approach that mixes the chemical functionalization of nano-systems with the use of single-electron transistors (SETs). I have observed the Coulomb-blockade single-electron transport response through magnetic gold nanoparticles and single-molecule magnet. In particular, Coulomb-blockade response of a Mn[sub4]-based SET device recorded at 240 mK revealed the appearance of two diamonds (two charge states) with a clear switch between one and the other is indicative of a conformational switching of the molecule between two different states. The excitations inside the diamonds move with magnetic field. The curvature of the excitations and the fact of having them not going down to zero energy for zero magnetic field, indicated the presence of magnetic anisotropy (zero-field splitting) in the molecule. In addition, the high magnetic field slope of the excitations indicates that transitions between charge states differ by a net spin value equal to 9 (|ΔS| = 9), as expected from the behavior of Mn4 molecules in their crystalline form. Anticrossings between different excitations are indicative of quantum superpositions of the molecular states, which are observed for the first time in transport measurements through and individual SMM.ID: 029810145; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 92-98).
Ph.D.
Doctorate
Physics
Sciences
29
Hossain, Mainul. « X-ray Radiation Enabled Cancer Detection and Treatment with Nanoparticles ». Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5309.
Texte intégralRésumé :
Despite significant improvements in medical sciences over the last decade, cancer still continues to be a major cause of death in humans throughout the world. Parallel to the efforts of understanding the intricacies of cancer biology, researchers are continuously striving to develop effective cancer detection and treatment strategies. Use of nanotechnology in the modern era opens up a wide range of possibilities for diagnostics, therapies and preventive measures for cancer management. Although, existing strategies of cancer detection and treatment, using nanoparticles, have been proven successful in case of cancer imaging and targeted drug deliveries, they are often limited by poor sensitivity, lack of specificity, complex sample preparation efforts and inherent toxicities associated with the nanoparticles, especially in case of in-vivo applications. Moreover, the detection of cancer is not necessarily integrated with treatment. X-rays have long been used in radiation therapy to kill cancer cells and also for imaging tumors inside the body using nanoparticles as contrast agents. However, X-rays, in combination with nanoparticles, can also be used for cancer diagnosis by detecting cancer biomarkers and circulating tumor cells. Moreover, the use of nanoparticles can also enhance the efficacy of X-ray radiation therapy for cancer treatment. This dissertation describes a novel in vitro technique for cancer detection and treatment using X-ray radiation and nanoparticles. Surfaces of synthesized metallic nanoparticles have been modified with appropriate ligands to specifically target cancer cells and biomarkers in vitro. Characteristic X-ray fluorescence signals from the X-ray irradiated nanoparticles are then used for detecting the presence of cancer. The method enables simultaneous detection of multiple cancer biomarkers allowing accurate diagnosis and early detection of cancer. Circulating tumor cells, which are the primary indicators of cancer metastasis, have also been detected where the use of magnetic nanoparticles allows enrichment of rare cancer cells prior to detection. The approach is unique in that it integrates cancer detection and treatment under one platform, since, X-rays have been shown to effectively kill cancer cells through radiation induced DNA damage. Due to high penetrating power of X-rays, the method has potential applications for in vivo detection and treatment of deeply buried cancers in humans. The effect of nanoparticle toxicity on multiple cell types has been investigated using conventional cytotoxicity assays for both unmodified nanoparticles as well as nanoparticles modified with a variety of surface coatings. Appropriate surface modifications have significantly reduced inherent toxicity of nanoparticles, providing possibilities for future clinical applications. To investigate cellular damages caused by X-ray radiation, an on-chip biodosimeter has been fabricated based on three dimensional microtissues which allows direct monitoring of responses to X-ray exposure for multiple mammalian cell types. Damage to tumor cells caused by X-rays is known to be significantly higher in presence of nanoparticles which act as radiosensitizers and enhance localized radiation doses. An analytical approach is used to investigate the various parameters that affect the radiosensitizing properties of the nanoparticles. The results can be used to increase the efficacy of nanoparticle aided X-ray radiation therapy for cancer treatment by appropriate choice of X-ray beam energy, nanoparticle size, material composition and location of nanoparticle with respect to the tumor cell nucleus.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
30
Das, Prajna Paramita. « Enhancement of photoactivity by synthesizing nanotube-nanoparticle composites of TIO₂ and CdS for generation of hydrogen via splitting of water ». abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1460754.
Texte intégral
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Garcia, Marisol. « TRULY NON INVASIVE GLUCOSE OPTICAL SENSOR BASED ON METAL NANOPARTICLES GENERATION ». Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2260.
Texte intégralRésumé :
Diabetes is a disease that causes many complications in human normal function. This disease represents the sixth-leading cause of death in USA. Prevention of diabetes-related complications can be accomplished through tight control of glucose levels in blood. In the last decades many different glucose sensors have been developed, however, none of them are really non invasive. Herein, we present the study of the application of gold and silver nanoparticles with different shapes and aspect ratios to detect glucose traces in human fluids such as tears and sweat. This is to our knowledge the first truly non invasive glucose optical sensor, with extraordinary limit of detection and selectivity. The best proven nanoparticles for this application were gold nanospheres. Gold nanospheres were synthesized using chloroauric acid tri-hydrated (HAuCl4.3H2O) in solution, in the presence of glucose and ammonia hydroxide. The higher the glucose concentration, the higher the number of nanoparticles generated, thus the higher the extinction efficiency of the solution. The linear dependence of the extinction efficiency of the gold nanoparticles solution with glucose concentration makes of this new sensor suitable for direct applications in biomedical sensing. Our approach is based on the well known Tollens test.M.S.
Department of Chemistry
Arts and Sciences
Industrial Chemistry
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Patel, Chetak. « ROOM TEMPERATURE SYNTHESIS AND SYSTEMATIC CHARACTERIZATION OF ULTRA-SMALL CERIA NANOPARTICLES ». Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4354.
Texte intégralRésumé :
Cerium oxide (ceria, CeO₂) is a rare earth oxide that has attracted wide-spread research interest because of its unique properties such as high mechanical strength, oxygen ion conductivity, oxygen storage capacity and autocatalytic property. In recent years, researchers have discovered that ceria nanoparticles (NPs) are capable of protecting cells from free radical induced damage. Interestingly, it was found that nanometer size (~ 5 nm) ceria can scavenge free radicals quite efficiently, thus acting as an anti-oxidant. This phenomenon has been explained based on the autocatalytic property of ceria NPs. Several methods have been developed for the synthesis of ceria NPs that include flame combustion, hydroxide co-precipitation, hydrothermal/solvothermal, microemulsion, sonochemical and microwave-assisted heating methods and sol-gel method. Ceria NPs synthesized by these methods are often highly aggregated. Furthermore, large scale synthesis of monodispersed CeO₂ NPs is quite challenging. Therefore it is desirable to synthesize ceria NPs in bulk quantity keeping its important properties intact, specifically free-radical scavenging property. The main goal of this study is therefore to synthesize ultra-small ([less than]5.0 nm), high quality monodispersed ceria NPs in large quantities. In this thesis work, I present a couple of room temperature techniques, dilute sodium hydroxide (NaOH) assisted and ethylenediamine (EN) assisted for the synthesis of nearly mono-dispersed, ultra-small ([less than]5 nm) and water-dispersible ceria NPs. Morphology and particle size of the ceria NPs were investigated through high resolution transmission electron microscopy (HRTEM). The HRTEM analysis confirmed the formation of 3.0 ± 0.5 nm size and 2.5 ± 0.2 nm size highly-crystalline ceria NPs when synthesized using dilute NaOH and EN as solvents, respectively.
The nanostructures were characterized by X-ray diffraction (XRD) studies to determine the crystal structure and phase purity of the products. The samples were also thoroughly characterized by X-ray photoelectron spectroscopy (XPS) to determine the oxidation state of cerium ions. The presence of the +3 and +4 oxidation states in the samples was also confirmed from the XPS analysis. The co-existence of these two oxidation states is necessary for their applications as free radical scavenger. The autocatalytic behaviors of the ceria NPs were investigated through a hydrogen peroxide test and monitored by UV-visible transmission spectroscopy.M.S.
Department of Chemistry
Sciences
Industrial Chemistry MS
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Tejpal, Jyoti. « The use of metal and metal oxide nanoparticles against biofilms ». Thesis, De Montfort University, 2016. http://hdl.handle.net/2086/13114.
Texte intégralRésumé :
The persistence of biofilms in hospital settings are associated with Healthcare Associated Infections (HCAI), causing increased morbidity, mortality and healthcare costs. The resistance of biofilms against commonly used hospital disinfectants has been well reported. Metal and metal oxide nanoparticles (NP) such as silver (Ag), copper (Cu), zinc oxide (ZnO) and copper oxide (CuO) exhibit antimicrobial properties against various pathogens. Methods: Biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus in a Centre for Disease Control (CDC) biofilm reactor and a 96 well plate was compared. A three stage approach including Minimum Biofilm Reduction Concentration (MBRC), R2 values and log(10) reductions was used to assess the efficacy of Ag and ZnO NPs both alone and in combination against P. aeruginosa and S. aureus biofilms. Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) was used to further assess the antimicrobial ability of the metal and metal oxide NPs. The prevention of P. aeruginosa and S. aureus adherence on Ag and ZnO thin film coating on silicon (Si) surfaces was also investigated, as well as icaC, ebpS and fnbB gene expression in S. aureus biofilms. Results: The CDC biofilm reactor demonstrated to be the most effective method for P. aeruginosa and S. aureus biofilm production in comparison to 96 well plates, with lower standard errors of the mean (SE) and higher replicability. Individual MBRC of ZnO and Ag NPs in suspension were 256 and 50 µg/ml for P. aeruginosa and 16 and 50 µg/ml for S. aureus respectively. The concentrations in combination were reduced by at least a half, with concentrations of 32/25 µg/ml of ZnO/Ag NPs in suspension resulting in a significant (p ≤0.05) reduction of 3.77 log(10) against P. aeruginosa biofilms and 8/12 µg/ml of ZnO/Ag NPs in suspension resulted in a 3.91 log(10) (p ≤0.05) against S. aureus biofilms. Both combinations showed an additive effect. Time point analysis confirmed that a 24 hour treatment is vital for any significant (p ≤0.05) antimicrobial activity. AAS data suggested that the Ag+ ions quenched Zn2+ ions, therefore the antimicrobial efficacy of the combination is mainly due to Ag+ ions. Damage of the biofilms from Ag and ZnO NPs was observed in the SEM imaging and energy dispersive X-ray (EDX) analysis confirmed the adherence of Zn and Ag within the biofilms. CLSM imaging showed dead (red) cells of P. aeruginosa and S. aureus biofilms throughout the depth of the biofilm. P. aeruginosa formation was reduced by 1.41 log(10) and 1.43 log(10) on Ag and ZnO thin film coatings respectively. For S. aureus, a reduction of 1.82 log(10) and 1.65 log(10) was obtained for Ag and ZnO coating respectively. Only low levels of ribonucleic acid (RNA) were achieved so no further gene analysis could occur. Conclusion: Reductions of ≥3 log(10) were observed for P. aeruginosa and S. aureus biofilm treatment with ZnO/Ag NP suspensions. It can be concluded that the ZnO/Ag NP suspensions had greater antimicrobial activity than Ag and ZnO coated surfaces owing to large concentrations of Ag+ and Zn2+ ions acting upon the biofilms. The slower release of ions from coated surfaces suggest an inadequate concentration of ions in the media, which are therefore unable to prevent biofilm formation as rapidly as NP suspensions, however provide a sustained release of ions over time. The results from this investigation propose that Ag and ZnO NPs in suspension could be a potential alternative to disinfectants for use in nosocomial environments against P. aeruginosa and S. aureus biofilms.
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Chen, Yanshuang. « The Effect of Inorganic Nanostructured Materials on Neurogenesis ». Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/421454.
Texte intégralRésumé :
BioengineeringM.S.
Damage and/or loss of functional neurons can lead to detrimental cognitive and paralyzing effects in humans. Prime examples of such negative situations are well documented in patients with Parkinson's and Alzheimer's disease. In recent years, the utilization of neural stem cells and their derivation into neurons have been the focus of many research endeavors. The main reason for this is because neural stem cells are multi-potent and can differentiate into neurons, astrocytes, and oligodendrocytes. The research that will be detailed in this thesis involves the potential use of inorganic nanostructured materials to efficiently deliver bioactive molecules (i.e., retinoic acid, kinase inhibitors) to cells that can modulate the differentiation potential of certain cells into neurons. Specifically, PC12 (derived from rat pheochromocytoma) cells, as a neural model, was treated with select nanostructured materials with and without neuron inducers (molecules and ions) and the results were analyzed via biochemical assays and live-cell fluorescence microscopy. This thesis will include an in depth look into the cytocompatibility of the tested nanostructured materials that include silica nanoparticles, titanate nanotube microspheres, and carbon microparticles.
Temple University--Theses
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Ghoshal, Amitabh. « Plasmon enhanced near-field interactions in surface coupled nanoparticle arrays for integrated nanophotonic devices ». Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4630.
Texte intégralRésumé :
Reflection measurements on nanoparticle arrays fabricated using electron-beam lithography confirm the predicted particle-grating interaction. An unexpected polarization-dependent splitting of the film-mediated collective resonance is successfully attributed to the existence of out-of plane polarization modes of the metal nanoparticles. In order to distinguish between the excitation of propagating surface plasmons and localized nanoparticle plasmons, spectrally resolved leakage radiation measurements are presented. Based on these measurements, a universally applicable method for measuring the wavelength dependent efficiency of coupling free-space radiation into guided surface plasmon modes on thin films is developed. Finally, it is shown that the resonantly enhanced near-field coupling the nanoparticles and the propagating surface plasmons can lead to optimized coupler device dimensions well below 10 micrometers].; The current thrust towards developing silicon compatible integrated nanophotonic devices is driven by need to overcome critical challenges in electronic circuit technology related to information bandwidth and thermal management. Surface plasmon nanophotonics represents a hybrid technology at the interface of optics and electronics that could address several of the existing challenges. Surface plasmons are electronic charge density waves that can occur at a metal-dielectric interface at optical and infrared frequencies. Numerous plasmon based integrated optical devices such as waveguides, splitters, resonators and multimode interference devices have been developed, however no standard integrated device for coupling light into nanoscale optical circuits exists. In this thesis we experimentally and theoretically investigate the excitation of propagating surface plasmons via resonant metal nanoparticle arrays placed in close proximity to a metal surface. It is shown that this approach can lead to compact plasmon excitation devices. Full-field electromagnetic simulations of the optical illumination of metal nanoparticle arrays near a metal film reveal the presence of individual nanoparticle resonances and collective grating-like resonances related to propagating surface plasmons within the periodic array structure. Strong near-field coupling between the nanoparticle and grating resonances is observed, and is successfully described by a coupled oscillator model. Numerical simulations of the effect of nanoparticle size and shape on the excitation and dissipation of surface plasmons reveal that the optimum particle volume for efficient surface plasmon excitation depends sensitively on the particle shape. This observation is quantitatively explained in terms of the shape-dependent optical cross-section of the nanoparticles.ID: 028917015; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 111-119).
Ph.D.
Doctorate
Optics and Photonics
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Tambosi, Reem. « Stress and toxicity of metal in photosynthetic bacteria : multi-scale study of the effects and the targets of metal ions and nanoparticles Silver and Copper Acute Effects on Membrane Proteins and Impact on Photosynthetic and Respiratory Complexes in Bacteria Silver Effect on Bacterial Cell Membrane Structure Investigated by Atomic Force and Scanning Electron Microscopes Cadmium and Copper Cross-tolerance. Cu+ alleviates Cd2+ toxicity, and both cations target heme and chlorophyll biosynthesis pathway in Rubrivivax gelatinosus Additive effects of metal excess and superoxide, a highly toxic mixture in bacteria ». Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL070.
Texte intégralRésumé :
L’usage intensif des métaux et des ions métalliques dans l'industrie et l'agriculture représente une menace sérieuse pour l'environnement et pour tous les êtres vivants en raison de la toxicité aiguë de ces ions. Cependant, cela peut aussi être un outil prometteur. En effet, les ions comme les nanoparticules d'argent sont très utilisés dans diverses applications médicales, industrielles et sanitaires. L'effet antimicrobien de ces nanoparticules est en partie lié aux ions Ag⁺ libérés et à leur capacité à interagir avec les membranes bactériennes. L'objectif de ce projet est d'étudier l'interaction entre un objet biologique (les bactéries) et des objets physiques (métaux), pour comprendre l'impact des métaux sous différentes formes (ions, nanoparticules et nanostructures) sur les cellules bactériennes en utilisant différentes approches: de physiologie, biochimie, génétique et de biologie cellulaire. Nous avons utilisé comme modèles biologiques, principalement la bactérie photosynthétique pourpre Rubrivivax (R.) gelatinosus, mais aussi Escherichia coli; et pour les objets physiques, nous avons utilisé l'argent comme métal principal mais aussi d'autres métaux (cuivre, cadmium et nickel) à titre de comparaison. Les principaux objectifs de ce travail sont: 1- d'étudier l'impact et les mécanismes de toxicité de ces ions métalliques / NPs sur les métabolismes bactériens respiratoire et photosynthétique. 2- Identifier des gènes bactériens impliqués dans la réponse à un excès d'ions Ag⁺. 3- Etudier l'internalisation et l'interaction des ions métalliques et des NP au sein des membranes biologiques. Ainsi, nous avons pu identifier, à la fois in vitro et in vivo, des cibles spécifiques d'ions Ag⁺ et Cu²⁺ dans la membrane des bactéries. Cela inclut des complexes impliqués dans la photosynthèse, mais également des complexes de la chaine respiratoire. Il a été démontré que les ions Ag⁺ et Cu²⁺ ciblent spécifiquement une bactériochlorophylle exposée au solvant dans les antennes de collecte de lumière du photosystème de la bactérie. Ceci présente également, à notre connaissance, la première preuve directe de dommages induits par des ions Ag⁺ sur les protéines membranaires impliquées dans ces métabolismes. Par ailleurs, nous avons également réalisé une étude comparative par microscopie (AFM/ MEB) de l'effet de l'Ag⁺ en solution ou des Ag-NPs synthétisés dans notre laboratoire, sur la morphologie des cellules bactériennesThe extensive use of metal ions in industry and agriculture represents a serious threat to the environment and to all living being because of the acute toxicity of these ions. However, it can also be a promising tool, silver ions and nanoparticles are some of the most widely used metals in various industrial and health applications. The antimicrobial effect of these nanoparticles is in part related to the released Ag⁺ ions and their ability to interact with bacterial membranes. The goal of this project is to study the interaction between biological subject (the bacteria) and physical objects (metals), and more specifically to understand the impact of metals in different forms (ions, nanoparticles and nanostructures) on the growth of the bacterial cells using different approaches : physiology, biochemistry, genetics and cell biology. We used as biological models, principally the purple photosynthetic bacterium Rubrivivax (R.) gelatinosus, but also Escherichia coli; and for physical objects, we used silver as main metal but also other metals (copper, cadmium and nickel) for comparison. The main objectives are: 1- to study the impact and the mechanisms of toxicity of these metallic ions/NPs on the bacterial respiratory and photosynthesis metabolisms. 2- To identify the bacterial genes involved in response to excess silver. 3- To study the internalization and interaction of metals ions and NPs within biological membranes. The results showed that we were able to identify, both in vitro and in vivo, specific targets of Ag⁺ and Cu²⁺ ions within the membrane of bacteria. This include complexes involved in photosynthesis, but also complexes involved in respiration. Ag⁺ and Cu²⁺ were shown to specificaly target a solvent exposed bacteriochlorophyll in the light harvesting antennae of the photosystem. This also presents, in our knowledge, the first direct evidence of silver ions damages to membrane proteins involved in these metabolisms. We also carried out a microscopy (AFM/ SEM) comparative study of the effect of Ag⁺ ions or Ag-NPs synthesized in our laboratory, on the bacterial cell morphology
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Haque, Md Firoze. « CONTROLLED DEPOSITION OF MAGNETIC MOLECULES AND NANOPARTICLES ON ATOMICALLY FLAT GOLD SURFACES ». Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2109.
Texte intégralRésumé :
In this thesis I am presenting a detailed study to optimize the deposition of magnetic molecules and gold nanoparticles in atomically flat surfaces by self-assembling them from solution. Epitaxially grown and atomically flat gold surface on mica is used as substrate for this study. These surfaces have roughness of the order one tenth of a nanometer and are perfect to image molecules and nanoparticles in the 1-10 nanometers range. The purpose of these studies is to find the suitable parameters and conditions necessary to deposit a monolayer of nano-substance on chips containing gold nanowires which will eventually be used to form single electron transistors by electromigration breaking of the nanowire. Maximization of the covered surface area is crucial to optimize the yield of finding a molecule/nanoparticle near the gap formed in the nanowire after electromigration breaking. Coverage of the surface by molecules/nanoparticles mainly depends on the deposition time and concentration of the solution used for the self-assembly. Deposition of the samples under study was done for different solution concentrations and deposition times until a self-assembly monolayer covering most of the surface area is obtained. Imaging of the surfaces after deposition was done by tapping-mode AFM. Analysis of the AFM images was performed and deposition parameters (i.e. coverage or molecule/particle size distribution) were obtained. The subjects of this investigation were a molecular polyoxometalate, a single-molecule magnet and functionalized gold nanoparticles. The obtained results agree with the structure of each of the studied systems. Using the optimized deposition parameters found in this investigation, single-electron transport measurements have been carried out. Preliminary results indicate the right choice of the deposition parameters.M.S.
Department of Physics
Sciences
Physics MS
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Patil, Swanand. « FUNDAMENTAL ASPECTS OF REGENERATIVE CERIUM OXIDE NANOPARTICLES AND THEIR APPLICATIONS IN NANOBIOTECHNOLOGY ». Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3156.
Texte intégralRésumé :
Cerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide nanoparticles identified variations in properties as a function of particle size and also due to doping with trivalent elements (La and Nd). It was found that the lattice parameter of cerium oxide nanoparticles increases with decrease in particle size. Also Raman allowed mode shift to lower energies and the peak at 464 cm-1 becomes broader and asymmetric. The size dependent changes in cerium oxide were correlated to increase in oxygen vacancy concentration in the cerium oxide lattice. The doping of cerium oxide nanoparticles with trivalent elements introduces more oxygen vacancies and expands the cerium oxide lattice further (in addition to the lattice expansion due to the size effect). The lattice expansion is greater for La-doped cerium oxide nanoparticles compared to Nd-doping due to the larger ionic radius of La compared to Nd, the lattice expansion is directly proportional to the dopant concentration. The synthesized cerium oxide nanoparticles were used to develop an electrochemical biosensor of hydrogen peroxide (H2O2). The sensor was useful to detect H2O2 concentrations as low as 1µM in water. Also the preliminary testing of the sensor on tomato stem and leaf extracts indicated that the sensor can be used in practical applications such as plant physiological studies etc. The nanomolar concentrations of cerium oxide nanoparticles were also found to be useful in decreasing ROS (reactive oxygen species) mediated cellular damages in various in vitro cell cultures. Cerium oxide nanoparticles reduced the cellular damages to the normal breast epithelial cell line (CRL 8798) induced by X-rays and to the Keratinocyte cell line induced by UV irradiation. Cerium oxide nanoparticles were also found to be neuroprotective to adult rat spinal cord and retinal neurons. We propose that cerium oxide nanoparticles act as free radical scavenger (via redox reactions on its surface) to decrease the ROS induced cellular damages. Additionally, UV-visible spectroscopic studies indicated that cerium oxide nanoparticles possess auto-regenerative property by switching its oxidation state between Ce3+ and Ce4+. The auto-regenerative antioxidant property of these nanoparticles appears to be a key component in all the biological applications discussed in the present study.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
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Colon, Jimmie. « Use of Cerium Oxide Nanoparticles For Protection Against Radiation-Induced Cell Death ». Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6218.
Texte intégralRésumé :
The ability of engineered cerium oxide nanoparticles to confer radioprotection was examined. Rat astrocytes were treated with cerium oxide nanoparticles to a final concentration of 10 nanomolar, irradiated with a single 10 Gy dose of ionizing radiation and cell death was evaluated by propidium iodine uptake at 24 and 48 hours after radiation insult. Treatment of rat astrocytes with nanoceria resulted in an approximate 3-fold decrease in radiation induced death. These results suggest that the nanoceria are conferring protection from radiation induced cell death. Further experiments with human cells were conducted. Human normal and tumor cells (MCF-7 and CRL8798) were treated with the same dosage of cerium oxide nanoparticles, irradiated and evaluated for cell survival. Treatment of normal cells (MCF-7) conferred nearly 99% protection from radiation-induced cell death while the same concentration of nanoceria showed almost no protection in tumor cells (CRL8798). TUNEL analysis results of similarly treated cells demonstrated that nanoceria reduced radiation-induced cell death by 3-fold in normal breast cells but not in MCF-7 tumor cell lines when cultured under the same conditions. We concluded that cerium oxide nanoparticles confer radioprotection in a normal human breast line (CRL 8798) but not in a human breast tumor line (MCF-7). It is hoped that the outcome of this study will guide future endeavors toward a better elucidation of the molecular pathways involved in the protection of cells with nanoceria against radiation-induced cell death, as well as the minimization of the bystander effect in radiation therapy.M.S.
Masters
Molecular Biology and Microbiology
Burnett College of Biomedical Sciences
Molecular and Microbiology
40
McKee, James. « Development and Characterization of Nanoparticlee Enhancements in Pyrolysis-Derived High Temperature Composites ». Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6320.
Texte intégralRésumé :
Thermal protection systems, which are commonly used to protect spacecraft during atmospheric entry, have traditionally been made of materials which are traditionally high in manufacturing costs for both the materials needed and the manufacturing complexity, such as carbon-carbon composites and aerogels. In addition to their manufacturing costs, these materials are also limited in their strength, such as PICA, in a way that necessitate the use of tiles as opposed to single structures because they are not capable of supporting larger structures. The limitations of polymer reinforced composites have limited their entry into these applications, except for pyrolyzed composite materials, such as carbon-carbon and ceramic composites. These materials have been successfully demonstrated their utility in extreme environments, such as spacecraft heat shields, but their high costs and the difficulty to manufacture them have limited their use to similarly high performance applications where the costs are justifiable.
Previous work by others with "fuzzy fiber" composites have shown that aligned carbon nanotubes (CNTs) grown on fibers can improve their thermal conductivity and wettability. To this end vertically aligned CNTs were studied for their potential use, but found to be difficult to process with current conventional techniques. A composite material comprised of basalt, a relatively new reinforcing fiber, and phenolic, which has been used in high-temperature applications with great success was made to attempt to create a new material for these applications. To further improve upon the favorable properties of the resulting composite, the composite was pyrolyzed to produce a basalt-carbon composite with a higher thermal stability than its pristine state. While testing the effects of pyrolysis on the thermal stability, a novel technique was also developed to promote in-situ carbon nanotube growth of the resulting basalt-carbon composite without using a monolithic piece of cured phenolic resin in place of the standard aromatic hydrocarbon-catalyst precursor. The in-situ growth of carbon nanotubes (CNTs) was explored as their thermal stability and effectiveness in improving performance has been previously demonstrated when used as a resin additive.
The specimens were examined with SEM, EDS, and TGA to determine the effects of both pyrolysis and CNT growth during pyrolysis of the basalt phenolic composites. These tests would confirm the presence of CNTs/CNFs directly grown in the composite by pyrolysis, and confirm their composition by EDS and Raman spectroscopy. EDS would additionally confirm that the surface of the basalt fibers possess a composition suitable for CNT growth, similar to the parameters of CVD processing. Additional testing would also show that the growth behavior of the CNTs/CNFs is dependent on temperature as opposed to composition, indicating that there is a threshold temperature necessary to facilitate the availability of catalysts from within the basalt fibers. The thermal stability shown by TGA indicates that the process of pyrolysis leaves the newly formed composite with a high degree of thermal stability, making the new materials potentially usable in applications such as turbines, in addition to large-scale thermal protection systems.M.S.M.S.E.
Masters
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering
41
Ahmed, Selver. « FORMATION, DYNAMICS AND CHARACTERIZATION OF SUPPORTED LIPID BILAYERS ON SiO2 NANOPARTICLES ». Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/213126.
Texte intégralRésumé :
ChemistryPh.D.
This work is devoted to understanding the formation of supported lipid bilayers (SLBs) on curved surfaces as a function of lipid properties such as headgroup charge/charge density and alkyl chain length, and nanoparticle properties such as size and surface characteristics. In particular, the formation of SLBs on curved surfaces was studied by varying the size of the underlying substrate SiO2 nanoparticles with size range from 5-100 nm. Curvature-dependent shift in the phase transition behavior of these supported lipid bilayers was observed for the first time. We found that the phase transition temperature, Tm of the SLBs first decreased with decreasing the size of the underlying support, reached a minimum, and then increased when the size of the particles became comparable with the dimensions of the lipid bilayer thickness; the Tm was above that of the multilamellar vesicles (MLVs) of the same lipids. The increase in Tm indicated a stiffening of the supported bilayer, which was confirmed by Raman spectroscopic data. Moreover, Raman data showed better lipid packing and increased lateral order and trans conformation for the SLBs with increasing the curvature of the underlying support and decrease of the gauche kinks for the terminal methyl groups at the center of the bilayer. These results were consistent with a model in which the high free volume and increased outer headgroup spacing of lipids on highly curved surfaces induced interdigitation in the supported lipids. These results also support the symmetric lipid exchange studies of the SLBs as a function of the curvature, which was found to be slower on surfaces with higher curvature. Further, the effect of surface properties on the formation of SLBs was studied by changing the silanol density on the surface of SiO2 via thermal/chemical treatment and monitoring fusion of zwitterionic lipids onto silica (SiO2) nanoparticles. Our findings showed that the formation of SLBs was faster on the surfaces with lower silanol density and concomitantly less bound water compared to surfaces with higher silanol density and more bound water. Since the two SiO2 nanoparticles were similar in other respects, in particular their size and charge (ionization), as determined by zeta potential measurements, differences in electrostatic interactions between the neutral DMPC and SiO2 could not account for the difference. Therefore the slower rate of SLB formation of DMPC onto SiO2 nanoparticles with higher silanol densities and more bound water was attributed to greater hydration repulsion of the more hydrated nanoparticles. Lastly, we have investigated the effect and modulation of the surface charge of vesicles on the formation of SLBs by using different ratios of zwitterionic and cationic DMPC/DMTAP lipids. Through these studies we discovered a procedure by which assemblies of supported lipid bilayer nanoparticles, composed of DMPC/DMTAP (50/50) lipids on SiO2, can be collected and released from bilayer sacks as a function of the phase transition of these lipids. The lipids in these sacks and SLBs could be exchanged by lipids with lower Tm via lipid transfer.
Temple University--Theses
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Darugar, Qusai A. « Surface effects on the ultrafast electronic relaxation of some semiconductor and metallic nanoparticles ». Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-06272006-160645/.
Texte intégralRésumé :
Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2007.Zhang, John, Committee Member ; Wang, Zhong, Committee Member ; El-Sayed, Mostafa, Committee Chair ; Orlando, Thomas, Committee Member ; Lyon, Andrew, Committee Member.
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Ben, slimen Fedia. « Caractérisation des verres luminescents préparés par la méthode sol-gel ». Thesis, Angers, 2016. http://www.theses.fr/2016ANGE0019/document.
Texte intégralRésumé :
Les verres dopés par des ions de terres rares ou/et des nanoparticules de semi-conducteurs continue à faire l’objet de plusieurs recherches grâce à leur efficacité dans les domaines d’optoélectroniques. En effet, ces matériaux sont parmi les candidats potentiels pour des applications en photonique tels que les amplificateurs à fibre optique, les convertisseurs de lumière, les capteurs et les guides d'ondes 3D.Dans le cadre de cette thèse, des verres à base de silice (SiO2)dopé par des ions d’europium (Eu3+) ont été préparés par le processus sol-gel. Afin de mieux disperser les ions de terres rares et d’améliorer leur émission, les verres ont été codopés par le phosphore et/ou l’aluminium. Des nanoparticules de semi-conducteur (CdS) ont été aussi introduite dans le verre afin d’augmenter l’absorbance de la lumière excitatrice et d’obtenir une émission plus intense des ions Eu3+. Les verres préparés ont été analysés par photoluminescence et par la technique de rétrécissement des raies de luminescence (FLN). Ces mesures ont été suivi par des simulations par la méthode de dynamique moléculaire (DM)afin d’étudier l’effet de phosphore et/ou de l’aluminium sur l’environnement local des ions d’europium et la dispersion de ces ions dans la matrice vitreuse. La présence de deux types de sites des ions d’europium dans le verre de silicophosphates a été mise en évidence et a été confirmé par les deux techniques (FLN et DM). L’effet des nanoparticules de CdS sur l'émission des ions Eu3+dans un verre de silicophosphate a été aussi étudié et il a été montré que l’émission des ions Eu3+ est considérablement dépendante de la concentration des nanoparticules de CdS et de la température de recuitGlasses doped with rare earth ions and/or semiconductor nanoparticles continues to be the subject of several studies due to their effectiveness in optoelectronic fields. Indeed, these materials are among the potential candidates for photonic applications such as optical fiber amplifiers, light converters, sensors and 3D waveguides. As part of this thesis, silica-based glasses (SiO2) doped with europium ions (Eu3+) were prepared by the sol-gel process. In order to better disperse the rare earth ions and improve their emission, the glasses were codoped with phosphorus and/or aluminum. Semiconductor nanoparticles (CdS) were also introduced into the glass in order to increase the absorbance of the excitation light and to obtain a more intense emission of Eu3+ ions. The prepared glasses were analyzed by photoluminescence and by the technique of Fluorescence line narrowing (FLN). These experimental measurements were followed by theoretical simulations using the molecular dynamics method (DM) to study the effect of phosphorus and/or aluminum on the local environment of the europium ions and their dispersion in the vitreous matrix. The presence of two types of europium ion sites in the glass silicophosphates has been demonstrated and confirmed by two techniques (FLN and DM). The effect of CdS nanoparticles on the emission of Eu3+ ions in a glass silicophosphate was also studied and it was shown that the emission of Eu3+ ions is considerably dependent on theconcentration of CdS nanoparticles and annealing temperature
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Torrance, David. « Influence of the Local Dielectric Environment and its Spatial Symmetry on Metal Nanoparticle Surface Plasmon Resonances ». Honors in the Major Thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1195.
Texte intégralRésumé :
This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Sciences
Physics
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Golze, Spencer. « Combining Nanoimprint Lithography with Dynamic Templating for the Fabrication of Dense, Large-Area Nanoparticle Arrays ». Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/369925.
Texte intégralRésumé :
Mechanical EngineeringM.S.
The study of nanomaterials is a developing science with potentially large benefits in the development of catalysts, optical and chemical sensors, and solid state memory devices. As several of these devices require large arrays of nanoparticles, one of the greatest obstacles in material characterization and device development is the reliable manufacture of nanopatterns over a large surface area. In addition, various applications require different nanoparticle size and density. High density arrays with small nanoparticle sizes are difficult to achieve over a large surface area using current manufacturing processes. Herein, Nanoimprint Lithography (NIL) and Dynamic Templating are combined to create a new manufacturing process capable of developing high density arrays with small nanoparticle sizes. The NIL process involves the stamping of a polymer coated substrate by a silicon stamp with patterned nanofeatures. The stamp is then removed, leaving the pattern in the polymer, which is first etched and then coated with a thin layer of metal, filling the recessed regions of the pattern. The excess polymer is dissolved, leaving a pattern of nanoparticles on the substrate matching the pattern on the stamp. When Dynamic Templating is applied, a very thin layer of metal can be coated, which forms small nanoparticle sizes when dewetted. A custom NIL system has been developed to combine these two processes together, which has now proven to yield consistent large-area, dense arrays with a small nanoparticle size. An array spacing of 700 nm has been achieved, along with a nanoparticle size of 90 nm. Arrays have been created in gold and palladium, where there is now the potential to combine them with other solution-based syntheses which should lead to complex nanoparticle geometries suitable for sensor applications.
Temple University--Theses
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Wen, Wucheng. « Development and Evaluation of Nano-herbal Therapy for Metastatic Breast Cancer Treatment ». Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/534260.
Texte intégralRésumé :
Pharmaceutical SciencesPh.D.
Triptolide (TPL), a diterpenoid triepoxide that is extracted from a traditional Chinese herb called Tripterygium Wilfordii (also known as ‘Thunder God Vine’) has recently drawn increasing interests from pharmaceutical and biomedical researchers, especially in the aspect of its potential efficacy on multiple cancer treatment. TPL has shown significant growth and proliferation inhibition activities in a broad range of cancer cell types. Moreover, it has shown the inhibition of osteoclastogenesis by breast cancer bone metastasis. However, due to its limitation in toxicity, solubility and non-specific biodistribution, it is challenging for the application of TPL in clinical study. Besides, TPL can rapidly distribute in most vital organs and no evidences shown tissue accumulation of drug. It is indispensable to overcome those barriers and optimize the properties and performance of the promising drug molecule. Lipid-based nanocarriers such as nanostructured lipid carriers (NLC) have been extensively studied for delivery of poorly-water soluble drug compounds. They also have the potential to optimize the physicochemical properties of the drug and may enhance a targeted delivery of the drug to specific therapeutic site. Alendronate (Fosamax®), an FDA approved bisphosphonate drug for osteoporosis, osteogenesis imperfecta and several other bone diseases, has been used as a bone targeting decoration agent. Breast cancer cell line MDA-MB-231 and other type of cancer cell lines have been used to study the in vitro cytotoxicity of TPL and the carriers while MC3T3-E1 cell line was used for toxicity assessment. Rats have also been used to study the in vivo performance of the drug. After modifying and optimizing the formulation of the particle, the formulation had the ability to remain structurally and functionally stable when being in the bio-simulated media at 37 °C and in water at room temperature with high encapsulation efficiency. In vitro study illustrated that both TPL free drug (stock solution 10mg/mL dissolved in DMSO) and TPL nanoparticle without alendronate (TPL-NP) had similar cytotoxicity on MDA-MB-231 and some other type of cancer cell lines. The ALE decoration on the particle (ALE-NP-TPL) has enhanced the anti-cancer effect especially with breast cancer cell line. The in vivo study shows that after 24 hours of the dose injection at local bone site, the formulation and TPL can remained at the location without random distribution to other organs. TPL-NP has not only successfully optimized the physicochemical properties of the drug, but also shows great enhancement of therapeutic effect both in vitro and in vivo study.
Temple University--Theses
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Nawotka, Alexis. « Evaluation of Small Unilamellar Vesicles as a Removal Method of Benzo[a]pyrene from Humic Substances in Soils ». Master's thesis, Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/592708.
Texte intégralRésumé :
GeologyM.S.
Polycyclic aromatic hydrocarbons (PAHs) are highly hydrophobic and lipophilic and are readily retained by soil surfaces and organic matter. Hence, several techniques have been developed in an effort to economically and effectively remove them from soil solids. Their strong affinity to soil organic matter limits their biodegradation processes by microorganisms, making them persistent in the soil environment. Recently, the use of “small unilamellar vesicles” (SUVs), nano-scale lipid aggregates, has been proposed as a means to enhance these microbial degradations, by effectively solubilizing lipophilic PAHs from the soil solids. In this thesis, laboratory-scale batch experiments were performed to examine this potential by measuring the uptake of benzo[a]pyrene (BaP), a model PAH compound, by SUVs from a simulated soil organic matter. This environmental surface was created by coating silica (SiO2) nanospheres with a layer of poly-L-lysine, followed by humic acid, and characterized by dynamic light scattering for particle size and zeta potential values. Then, these humic acid-bound SiO2 particles were saturated with BaP and then equilibrated with SUVs. The uptake of BaP by SUVs was measured through fluorescence spectroscopy, and the average amount of BaP concentrated in the 1 mg/L humic acid-bound SiO2 particles was found to be 1.77 µg/L. After one week of equilibration with SUVs, 94.4% and 83.6% of the added BaP was solubilized by SUVs (in solutions containing 50 mg/L and 100 mg/L of vesicles, respectively), indicating an excellent ability to extract BaP from the soil organic particles. SUVs can therefore be an effective vehicle to enhance the biodegradability of PAHs in soils, with potential as an environmentally sustainable and affordable method.
Temple University--Theses
48
Besson, Sophie Marie Catherine. « Films organisés de silice mésoporeuse : Synthèse, caractérisation structurale et utilisation pour la croissance de nanoparticules ». Palaiseau, Ecole polytechnique, 2001. http://www.theses.fr/2002EPXX0012.
Texte intégral
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Croy, Jason Robert. « Supported mono and bimetallic platinum and iron nanoparticles electronic, structural, catalytic, and vibrational properties ». Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4652.
Texte intégralRésumé :
Catalysis technologies are among the most important in the modern world. They are instrumental in the realization of a variety of products and processes including chemicals, polymers, foods, pharmaceuticals, fuels, and fuel cells. As such, interest in the catalysts that drive these processes is ongoing, and basic research has led to significant advances in the field, including the production of more environmentally friendly catalysts that can be tuned at the molecular/atomic level. However, there are many factors which influence the performance of a catalyst and many unanswered questions still remain. The first part of this work is concerned with the factors that influence the catalytic properties (activity, selectivity, and stability) of supported Pt and Pt-M nanoparticles (NPs). These factors are a synergistic combination of size, composition, support, oxidation state, and reaction environment (i.e. adsorbates, temperature, pressure, etc.). To probe the catalytic properties of complex and dynamic NP systems we have used MeOH decomposition and oxidation reactions, each of which has significant environmental and economic potential. We have given some emphasis to the state of NP oxidation, and with the aid of X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD), have followed the formation and temperature-dependent evolution of oxide species on Pt NPs. Further, we have explored how these species behave under the conditions of our probe reactions using a packed-bed mass flow reactor coupled to a quadrupole mass spectrometer (QMS). To carry out our investigations we exploit a NP synthesis method which is rather novel to nanocatalysis, micelle encapsulation. Since most available experimental techniques give information on ensemble averages, control over size distributions in NP samples is critical if unambiguous results are to be obtained. Micelle encapsulation allows us this control with several unique, inherent advantages.; It is to this end that micelle encapsulation has allowed us to probe the detailed structure of small (~1 nm), supported, Pt NPs with extended X-ray absorption fine structure spectroscopy (EXAFS). Furthermore, we were able to explore experimentally, for the first time, the vibrational density of states (VDOS) of supported, isolated, monodispersed, mono and bimetallic NP systems via nuclear resonant inelastic X-ray scattering (NRIX). These synchrotron-based techniques (EXAFS, NRIXS) rely heavily on the monodispersity of the NP ensemble for reliable information.ID: 028916773; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 204-229).
Ph.D.
Doctorate
Department of Physics
Sciences
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Tangeysh, Behzad. « SIZE-CONTROLLED SYNTHESIS OF TRANSITION METAL NANOPARTICLES THROUGH CHEMICAL AND PHOTO-CHEMICAL ROUTES ». Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/327946.
Texte intégralRésumé :
ChemistryPh.D.
The central objective of this work is developing convenient general procedures for controlling the formation and stabilization of nanoscale transition metal particles. Contemporary interest in developing alternative synthetic approaches for producing nanoparticles arises in large part from expanding applications of the nanomaterials in areas such as catalysis, electronics and medicine. This research focuses on advancing the existing nanoparticle synthetic routes by using a new class of polymer colloid materials as a chemical approach, and the laser irradiation of metal salt solution as a photo-chemical method to attain size and shape selectivity. Controlled synthesis of small metal nanoparticles with sizes ranging from 1 to 5nm is still a continuing challenge in nanomaterial synthesis. This research utilizes a new class of polymer colloid materials as nano-reactors and protective agents for controlling the formation of small transition metal nanoparticles. The polymer colloid particles were formed from cross-linking of dinegatively charged metal precursors with partially protonated poly dimethylaminoethylmethacrylate (PDMAEMA). Incorporation of [PtCl6]2- species into the colloidal particles prior to the chemical reduction was effectively employed as a new strategy for synthesis of unusually small platinum nanoparticles with narrow size distributions (1.12 ± 0.25nm). To explore the generality of this approach, in a series of proof-of-concept studies, this method was successfully employed for the synthesis of small palladium (1.4 ±0.2nm) and copper nanoparticles (1.5 ±0.6nm). The polymer colloid materials developed in this research are pH responsive, and are designed to self-assemble and/or disassemble by varying the levels of protonation of the polymer chains. This unique feature was used to tune the size of palladium nanoparticles in a small range from 1nm to 5nm. The procedure presented in this work is a new convenient room temperature route for synthesis of small nanoparticles, and its application can be extended to the formation of other transition metals and alloy nanoparticles. This research also focuses on developing new photo-chemical routes for controlling the size and shape of the nanoparticles through high-intensity ultra-fast laser irradiation of metal salt solution. One of the core objectives of this work is to explore the special capabilities of shaped laser pulses in formation of metal nanoparticles through irradiation of the solutions by using simultaneous spatial and temporal focusing (SSTF). Femtosecond laser irradiation has not yet been widely applied for nanoparticle synthesis, and offers new regimes of energy deposition for synthesis of nanomaterials. Photo-reduction of aqueous [AuCl4]- solution to the gold nanoparticles (AuNPs) has been applied as a model process for optimizing the experimental procedures, and evaluating the potential of shaped laser pulses in the synthesis of AuNPs. Systematic manipulation of the laser parameters and experimental conditions provided effective strategies to control the size of Au nanoparticles in strong laser fields. Varying the concentration of polyethylene glycol (PEG45) as a surfactant effectively tuned the size of AuNPs from 3.9 ±0.7nm to 11.0 ±2.4nm, and significantly increased the rate of Au(III) reduction during irradiation. Comparative studies revealed the capability of shaped laser pulses in the generation of smaller and more uniform AuNPs (5.8 ±1.1nm) relative to the other conventional laser irradiation methods (7.2 ±2.9nm). Furthermore, a new laser-assisted approach has been developed for selective formation of triangular Au nanoplates in the absence of any surfactant molecule. This method relies on rapid energy deposition by using shaped, ultra-intense laser pulses to generate Au seeds in aqueous [AuCl4]- solution, and the slow post-irradiation reduction of un-reacted [AuCl4]- species by using H2O2 as a mild reducing agent. Variation of the laser irradiation-time was found as an effective strategy to tune the morphology of Au nanomaterials from nanospheres to triangular nanoplates. The surfactant-free Au nanoplates produced in this research can be readily functionalized with a variety of target molecules or surfactants for desirable applications such as biomedicine. The concept of rapid laser processing followed by in situ chemical reduction can be expanded as a general methodology for high-yield production of nanomaterials, and provides a series of new laser dependent parameters for controlling the nanoparticle formation.
Temple University--Theses